Porphyry
Porphyritic Andesite/Basalt
Category
Browse igneous or sedimentary (water worn) specimens identified by the Rock Identifier community.
Porphyry
Porphyritic Andesite/Basalt
Jasper (Yellow/Brown)
Silicon Dioxide (SiO2) with impurities
Banded Chert (River Stone)
Silicon Dioxide (SiO2)
Yellow Chalcedony (Agate Pebble)
Silicon Dioxide (SiO2)
Yellow Quartzite or Yellow Jasper
Quartzite (primarily SiO2 with Iron oxide staining)
Basalt Pebble
Basalt (Mafic volcanic rock)
Basalt
Basalt (dominated by plagioclase feldspar and pyroxene)
Granite Pebble
Felsic Intrusive Igneous Rock (composed of Quartz, Alkali Feldspar, and Plagioclase)
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
Diabase (Greenstone)
Diabase or Dolerite
Basalt with Magnetite
Crystalline Basalt (Primarily Plagioclase and Pyroxene) with Magnetite (Fe3O4)
Riverstone (Quartzite or Siltstone cobble)
Quartzite (primarily SiO2)
Jasper
Silicon dioxide (SiO2) with impurities
Basalt River Cobble
Basalt (Aphanitic Mafic Volcanic Rock)
Quartz (River Pebble)
Quartz (Silicon Dioxide - SiO2)
Milky Quartz Cobble
Silicon Dioxide (SiO2)
White Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
Milky Quartz
Silicon Dioxide (SiO2)
Black Spinel
Magnesium Aluminum Oxide (MgAl2O4)
Milky Quartz Pebble
Silicon Dioxide (SiO2)
Quartz Pebble
Silicon Dioxide (SiO2)
Jasper (Red Jasper)
Silicon Dioxide (SiO₂)
Moss Agate
Cryptocrystalline Quartz (SiO2 with Manganese or Iron Oxide inclusions)
Sandstone
Arenite (SiO2-rich)
Conglomerate
Conglomerate (Detrital Sedimentary Rock)
Banded Chert
Sedimentary Cryptocrystalline Quartz (SiO2)
Banded Iron Formation (Jasper-Hematite)
Banded Iron Formation (BIF); composition primarily Hematite (Fe2O3) and Chalcedony/Quartz (SiO2)
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
Quartz (River Pebble)
Silicon Dioxide (SiO2)
Chert (often called Flint or Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Granite Cobble
Phaneritic Felsic Igneous Rock (Granite)
Quartz Pebble
Silicon Dioxide (SiO2)
Chert (Jasper/Flint variety)
Microcrystalline quartz (SiO2)
Chert (Pebble)
Microcrystalline silica (SiO2)
Chert (Pebble)
Chert (Microcrystalline Quartz, SiO2)
Yellow Chert (River Stone/Pebble)
Chert (Cryptocrystalline Quartz, SiO2)
Chert (Jasper variety)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
River Cobble (likely Basalt)
Mafic Igneous Rock (Aphanitic)
Jasper
Silicon dioxide (SiO2) with impurities
Sandstone, Quartzite, and River Pebbles
Silicon Dioxide (SiO2) based Sedimentary/Metamorphic structures
Sandstone Pebble
Arenite (primarily Quartz, SiO2)